A diantimony pentoxide sol is one which is used as a flame retarding adjuvant for plastics, fibers, etc., as a microfiller for a surface treating agent for plastics or glass, as an inorganic ion exchanger, as a catalyst component, as a pigment component, etc. Usually, a highly concentrated sol (containing from 30 to 50 wt % of Sb2O5) stabilized by an organic base, is used. Heretofore, as diantimony pentoxide sols, those obtained by the following methods have been known.
Namely, a method of deionizing an alkali metal antimonate by a cation exchange resin (Patent Documents 1 and 2), a method of reacting an alkali metal antimonate with an inorganic acid, followed by peptization (Patent Documents 3 and 4), etc. have been known.
As a method other than the above, a method of oxidizing diantimony trioxide with an aqueous hydrogen peroxide solution at a high temperature has been reported (Patent Documents 5, 6, 7 and 8). Further, a method of adding an inorganic alkaline substance at the time of the oxidation reaction of diantimony trioxide with an aqueous hydrogen peroxide solution, to control the particle size, has been reported (Patent Documents 9, 10 and 11).
Further, a method for preparing a sol showing excellent stability at the time of preparing an organo sol, is disclosed wherein an oxidation reaction of diantimony trioxide with an aqueous hydrogen peroxide is carried out in the presence of from 0.1 to 50 wt %, as SiO2, of an inorganic silicic compound (Patent Document 12).
Further, as an example for application of high purity diantimony pentoxide, a fining agent for glass may be mentioned. Heretofore, it has been known that when glass raw material is melted, bubbles contained in molten glass will remain to deteriorate the transparency. For the purpose of preventing the deterioration of the transparency, a fining agent is used. As such a fining agent, diantimony trioxide and an oxidizing agent (such as sodium nitrate) are added to the molten glass, whereby the diantimony trioxide is changed to diantimony pentoxide, and thereafter, at a higher glass melting temperature, the diantimony pentoxide will be decomposed to diantimony trioxide. By oxygen generated at that time, the bubbles will be grown, whereby removal of bubbles contained in the glass will be accelerated. However, at the same time, nitrogen oxide will be formed, such being undesirable from the viewpoint of the environment, and further, such a method can not be applied to the production of alkali-free glass, since an alkali metal is incorporated in the glass. Under the circumstances, it is being studied to use diantimony pentoxide alone as a fining agent for glass (Patent Document 13).
Patent Document 1: U.S. Pat. No. 4,110,247
Patent Document 2: JP-B-57-11848
Patent Document 3: JP-A60-41536
Patent Document 4: JP-A-61-227918
Patent Document 5: JP-B-53-20479
Patent document 6: JP-A52-21298
Patent Document 7: JP-A-52-123997
Patent Document 8-JP-A-52-131998
Patent Document 9: JP-A-59-232921
Patent Document 10: JP-A-60-137828
Patent Document 11: JP-A-2-180717
Patent Document 12: JP-B-7-25549
Patent Document 13: JP-A-11-49520